title: Stability-indicating HPLC assays for the determination of piritramide and droperidol in PCA solution.
abstract: OBJECTIVE
  A mixture of morphine and droperidol is a well-established antiemetic for reducing the risk of postoperative nausea and vomiting. A mixture of piritramide and droperidol has not yet been evaluated in this context. Our objectives were to develop a high-performance liquid chromatographic assay for piritramide and droperidol in 0·9% saline, and to establish their stability under defined storage conditions.
  
  
  METHODS
  The separation and assay of both drugs were attempted by high performance liquid chromatography (HPLC) using a RP-select B column and a mobile phase of 57:43% v/v methanol-monosodium phosphate solution 0·05 M at a flow rate of 1·2 mL/min. UV detection at 205 and 246 nm for piritramide and droperidol were used, respectively.
  
  
  CONCLUSIONS
  The HPLC method was successful. Linearity was shown for piritramide from 0·075 to 0·013 mg/mL and for droperidol from 0·8 to 0·2 mg/mL. The intra- and inter-day relative standard deviation (RSD, %) was 0·27% and 0·54% for piritramide and droperidol, respectively. The two drugs were stable for at least 72 h when stored under ambient light at room temperature.
  
  
  CONCLUSIONS
  Seventy-five milligrams piritramide and 2·5 mg droperidol diluted to 50 ml with 0·9% saline should be suitable for clinical use. At this dilution, a Dipidolor(®) and Xomolix(®), mixture, was stable when stored under ambient light exposure at room temperature for at least 72 h.
authors.affiliation: Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Selbach
authors.forename: W E
authors.initials: WE
authors.lastname: Diederich
authors.forename: S
authors.initials: S
authors.lastname: Fett
authors.forename: D
authors.initials: D
authors.lastname: Fründ
authors.forename: T
authors.initials: T
authors.lastname: Koch
authors.forename: L H J
authors.initials: LH
authors.lastname: Eberhart
mesh_terms: D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000032:analysis*; D000932:Antiemetics / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004329:Droperidol / Q000032:analysis*; D004355:Drug Stability; D006801:Humans; D019999:Pharmaceutical Solutions / Q000032:analysis; D010892:Pirinitramide / Q000032:analysis*; D020250:Postoperative Nausea and Vomiting / Q000139:chemically induced / Q000188:drug therapy* / Q000517:prevention & control*
chemical_list: D000701:Analgesics, Opioid; D000932:Antiemetics; D019999:Pharmaceutical Solutions; D010892:Pirinitramide; D004329:Droperidol